x1 is electricity [electric charge or current] in/on x2 of polarity/quantity x3 (def. negative).
(x3, a quantifier, can be expressed as a simple polarity using the numerals for positive and negative ma'u and ni'u); (explicitly) negative (= dutydikca), positive (= mardikca); current (= selmuvdikca, muvdikca; again default negative/electron current), charge (= klodikca, stadikca). See also lindi, xampo, flecu, maksi, tcana.